As a light homogenization device to homogenize luminance distribution of light emitted from an illumination light source, a light homogenization device using an optical integrator is disclosed in the Patent Literature 1 below.
This optical integrator is composed of a rod integrator formed by a glass rod of an inner-surface reflection type using an optical material such as quartz glass or fluorite.
The rod integrator can emit light having homogenized luminance distribution from an emitting surface thereof by propagating light entering from a incident surface thereof with total reflection.
However, when a plurality of rays of light having different spread angles enters from an incident surface of a rod integrator with a same incident angle, even though the luminance distribution of each of the rays of light is homogenized, the plurality of rays of light is emitted from the emitting surface of the rod integrator while their spread angles are still different to each other. Therefore, a projection optical system is used to project an image on the emitting surface of the rod integrator.